Apart from that, the game rules help play a game world. The rules directly affect the game world, as do the rulings of the GM, and all actions of characters, and creatures, and so on, that are to a certain extent constrained by rules, and rulings.
Most rules are oriented towards player characters, or rather the players. Players can feel the developing power of their characters, if there are options for meaningful interaction with the game world. Dice roll modifications are mere dice roll modifications - until they constrain the options of interacting with the game world.
Players of fighter characters may feel more powerful, if they can support with combat tactics: e.g. set up an ambush with the party, explain the tactics, and grant each party member a +2 attack bonus for the duration of that encounter. Here, the dice roll modifier underlines the influence of the character action on the whole group.
From my experience as a GM, it were options like these, as well, as special items, personal quests, and such, that helped players develop their characters, more than any class-based dice roll modifier.
And from my experience as a player, that +1 bonus rarely meant anything. It's the options of meaningful interaction with the game world. Allow that, and you players will explore, and develop a game world with you.
